For me this seems just about transparent. I went ff123 page and when I do the sweep I can hear right to the end(When I did sweep on my setup at work it stopped at 16khz). But testing on his mustange clips and every music track I have ripped, show it is impossible for me to distinguish --lowpass 16 (except on sweep).

I also ran the various test waves (castanets etc.) and it seemed to cope very well.

I am running spdif digital out from my Nforce MB to my denon 1802, an into to my Koss R80s Phones or Paradigm monitor 3s. Sounds perfect to me.

I was going to test the corresponding ABR setting, but I don't see the point anymore. Since I really cant distinguish this from the original WAV file (in music tracks). I did note a difference here or there on some specific test clips, but they were extremely minor.